1. Field of the Invention
The present invention relates to a clutch valve system for use in a static hydraulic continuously variable transmission in which a hydraulic circuit is formed between a swashplate type hydraulic pump and a swashplate type hydraulic motor, wherein the short-circuiting and the disconnection between the discharge side and the suction side of a hydraulic pump are controlled to control the transmission of power from the hydraulic pump to the hydraulic motor.
2. Description of the Prior Art
Such a conventional clutch valve system is constituted, as described in Japanese Patent Publication No. 38467/84, such that a higher pressure oil chamber connected to a discharge port of a hydraulic pump and a lower pressure oil chamber connected to a suction port of the hydraulic pump are defined at the end of a hydraulic motor, and clutch valves for permitting the short-circuiting and disconnection between both the oil chambers are disposed at the central portion of a support shaft for the hydraulic motor.
With the conventional arrangement, the clutch valves and a system for operating the clucth valves are axially protruded from the end of the hydraulic motor, resulting in an increased entire length of the transmission. This is a hindrance to a compact construction of transmission. Particularly, when the hydraulic pump and the hydraulic motor are coaxially arranged, the employment of the conventional clutch valve system results in a further increased entire length of the transmission.